CN110190326B

CN110190326B - Application of fullerene derivative as electrolyte additive and corresponding metal battery

Info

Publication number: CN110190326B
Application number: CN201910459207.8A
Authority: CN
Inventors: 谢佳; 姜智鹏; 韩智龙; 孙玉龙
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2019-05-29
Filing date: 2019-05-29
Publication date: 2021-08-31
Anticipated expiration: 2039-05-29
Also published as: CN110190326A

Abstract

The invention belongs to the field of secondary batteries, and discloses application of a fullerene derivative as an electrolyte additive and a corresponding metal battery. According to the invention, the fullerene derivative is introduced into the electrolyte of the metal battery as an electrolyte additive (except for the electrolyte additive with single component which is only composed of the fullerene derivative, the electrolyte additive with multiple components which is composed of the fullerene derivative and other components in a matching way) to obtain the corresponding metal battery, on one hand, the fullerene derivative can react with the metal cathode to generate a layer of stable passivation film in situ, so that the direct contact between the metal cathode and the electrolyte is blocked, the consumption of metal is reduced, the cycle life of the battery is prolonged, on the other hand, the reacted fullerene can be deposited on the surface of the metal cathode to enable the metal to be uniformly deposited, so that the generation of dendritic crystals is reduced, and the safety performance of the battery is improved.

Description

Application of fullerene derivative as electrolyte additive and corresponding metal battery

Technical Field

The invention belongs to the field of secondary batteries, and particularly relates to application of a fullerene derivative as an electrolyte additive and a corresponding metal battery, which correspond to a novel electrolyte additive for the metal battery and application thereof.

Background

The metal battery is a battery taking a metal simple substance as a main component of a negative electrode material, and taking a lithium metal battery as an example, the lithium metal battery has high specific capacity (3860mA/g) and the lowest potential (-3.04 vs standard hydrogen electrode). The metal lithium as a negative electrode can be used for lithium-sulfur batteries, lithium air batteries, embedded positive lithium batteries, lithium oxide positive batteries and the like, and is a hotspot of research on high-energy-density secondary batteries. However, lithium dendrite growth and SEI film cracking of the lithium metal negative electrode during cycling cause safety and cyclicity problems, respectively, for the metal lithium battery, and the development and commercialization of the lithium metal negative electrode are affected. Other metal batteries, such as sodium metal batteries, potassium metal batteries, zinc metal batteries, and the like are also similar.

The solution for lithium metal cathodes is mainly to control the morphology of the lithium deposition and to form a more stable SEI film on top. FromBased on the above two points, Zhang Qiang et al of Qinghua university adds polysulfide (Li) into LiTFSI salt electrolyte containing lithium nitrate₂S_x) To form an SEI film strengthening grain boundaries, thereby increasing the transport rate of lithium ions to obtain a uniform deposition surface (Energy Storage Materials 201810: 199-. However, this solution is not always feasible and the additive does not maintain its performance after being continuously consumed. Zhang Guanguang et al, northern Western countries, USA, developed a local high concentration electrolyte that accelerated lithium ion transport by improving the principle of solvation structure in the electrolyte, homogenized lithium metal deposition and inhibited the growth of dendrites on the surface of lithium metal (Adv Mater 201830 (21): e 1706102). However, since the high-concentration electrolyte contains a large amount of lithium salt, the production cost is too high, and it is difficult to apply it to practical production. Therefore, finding efficient and sustainable electrolyte additives is an important step to solve the problems of metal anodes, including lithium metal anodes.

Disclosure of Invention

In view of the above-mentioned drawbacks and needs of the prior art, an object of the present invention is to provide an application of fullerene derivatives as electrolyte additives and a corresponding metal battery, by introducing a fullerene derivative as an electrolyte additive (in addition to a single-component electrolyte additive composed of only a fullerene derivative, or an electrolyte additive composed of a plurality of components in which a fullerene derivative is mixed with other components) into an electrolyte of a metal battery, and obtaining a corresponding metal battery, on one hand, the metal battery can react with the metal cathode to generate a layer of stable passive film in situ, therefore, the direct contact between the metal cathode and the electrolyte is blocked, the consumption of metal is reduced, the cycle life of the battery is prolonged, and on the other hand, the fullerene after reaction can be deposited on the surface of the metal cathode to ensure that the metal is uniformly deposited, so that the generation of dendritic crystals is reduced, and the safety performance of the battery is improved. Taking a lithium metal battery as an example, the invention can solve the problem that an unstable solid phase interface is generated by the reaction of a conventional metal cathode and an electrolyte in a circulation process and the problem that the circulation performance is reduced by dead lithium generated by the reaction of the metal cathode and the electrolyte.

In order to achieve the above object, according to one aspect of the present invention, there is provided use of a fullerene derivative as an electrolyte additive, characterized in that the fullerene derivative is added to an electrolyte of a metal battery, particularly as an electrolyte additive.

As a further preferred aspect of the present invention, the fullerene derivative is specifically added to the electrolyte of the metal battery as a single-component additive or an electrolyte additive which is compounded with other components to form a multi-component electrolyte; wherein the other components are one or more of fluorinated carbonate, lithium nitrate, lithium polysulfide, lithium fluoride and vinylene carbonate.

As a further preferred aspect of the present invention, the fullerene derivative is specifically one or more of fullerene polychloride, fullerene polyfluoride, fullerene polybromide, fullerene polyiodide, fullerene polynitroide, fullerene polycarboxylic acid compound, fullerene multiester-based compound, fullerene polyhydroxyl compound, fullerene polyamino compound, fullerene polypiperazine compound and fullerene polysulfonamide compound.

In a further preferred embodiment of the present invention, the concentration of the fullerene derivative additive in the electrolyte solution is 0.1mM-100mM, preferably 1 mM.

According to another aspect of the present invention, there is provided a metal battery comprising a positive electrode material, a negative electrode material, a separator, and an electrolyte, characterized in that the electrolyte is mainly composed of an electrolyte additive and a matrix electrolyte, and the electrolyte additive includes a fullerene derivative.

As a further preferred aspect of the present invention, the above-mentionedThe working current of the electrolyte is 0.01mA cm^-2～ 100mA cm^-2Preferably 0.5mA cm^-2。

As a further preferred aspect of the present invention, the matrix electrolyte is one or more selected from ether electrolyte, ester electrolyte, ether ester mixed electrolyte, and ionic liquid electrolyte.

As a further preferable mode of the invention, the positive electrode material is one or more of lithium iron phosphate, lithium cobaltate, lithium titanate, lithium manganate, nickel-cobalt-manganese ternary, nickel-cobalt-aluminum ternary, sulfur, oxygen, carbon dioxide and air; the negative electrode material is one of metal lithium, metal sodium, metal potassium, metal zinc, metal magnesium and metal aluminum;

the diaphragm is selected from PP diaphragm, PE diaphragm, PP/PE/PP diaphragm and Al₂O₃Coating diaphragm, glass fiber diaphragm, PVDF diaphragm, PET/Al₂O₃One or more of a diaphragm, a cellulose diaphragm and an aramid diaphragm.

Compared with the prior art, the fullerene derivative (C60Xn) can be used as the electrolyte additive, the electrolyte additive can react with the metal cathode material to generate a stable passivation film in situ, so that the metal cathode is prevented from directly contacting with the electrolyte, the consumption of the metal cathode is reduced, the cycle life of the battery is prolonged, and the fullerene after reaction can be deposited on the surface of the metal cathode to enable the metal to be uniformly deposited, so that the generation of dendrites is reduced, and the safety performance of the battery is improved. Taking a lithium metal battery as an example, the electrolyte additive in the invention can react with lithium metal to generate a stable passivation film in situ, thereby preventing the direct contact of the lithium metal and the electrolyte, reducing the consumption of lithium and prolonging the cycle life of the battery, and on the other hand, the reacted fullerene can be deposited on the surface of the lithium metal to ensure that the lithium is uniformly deposited, thereby reducing the generation of lithium dendrites and improving the safety performance of the battery.

Because the existing metal cathode still has the characteristics of unstable chemical property, poor cycle performance and low capacity retention rate, the metal battery is difficult to produce on a large scale and realize commercialization. The invention thus provides an electrolyte additive that stabilizes a metal anode. The electrolyte additive can react with metal to generate a stable passivation film in situ, so that direct contact between the metal and the electrolyte is blocked, lithium consumption is reduced, the cycle life of the battery is prolonged, and fullerene after reaction can be deposited on the surface of the metal to enable lithium to be uniformly deposited, so that dendritic crystals are reduced, the surface of the metal is flattened, and the safety performance of the battery is improved. The method has the advantages of simple process, low cost, realization of large-scale industrial production and extremely high commercial value.

The research to which the present invention relates is quite innovative because fullerene is not suitable for application in the field of secondary batteries in past experience, and fullerene is of little interest in past research due to its excessively stable structure and poor solubility. Therefore, the invention develops a new method, uses a novel fullerene derivative additive, utilizes the characteristic that the solubility of fullerene in electrolyte is improved, and in addition, due to the characteristic that the fullerene derivative is unique and is easy to carry out reduction reaction with a metal simple substance to remove surface functional groups, a special protective film is further generated by further reaction.

In addition, the invention also introduces specific surface functional groups on the fullerene to form fullerene-rich polychloride, fullerene-rich polyfluoride, fullerene polybromide, fullerene polyiodide, fullerene-rich polynitroide, fullerene polycarboxylic acid compound, fullerene multiester base compound, fullerene polyhydroxy compound, fullerene polyamino compound, fullerene polypiperazine compound and fullerene polysulfonamide compound, wherein the fullerene derivatives have excellent solubility, and elements related to the derivative functional groups can promote the metal surface to generate a firm protective film, thereby playing a good role in protection.

Drawings

Fig. 1 is a graph of symmetrical battery cycle data for example 1 assembled in an ester electrolyte using the electrolyte additive proposed by the present invention.

FIG. 2 is a scanning electron micrograph of cycled lithium plates of a symmetrical cell assembled according to example 1 using the electrolyte additive proposed by the present invention.

Fig. 3 is a graph of symmetrical battery cycle data for example 2 assembled in ether electrolyte using the electrolyte additive proposed by the present invention.

Fig. 4 is a graph of the symmetrical cell cycle data for example 4 using the electrolyte additive proposed by the present invention for the synergistic effect with lithium nitrate in ether electrolyte.

Fig. 5 is a coulombic efficiency test chart of a half cell assembled by using the electrolyte additive proposed by the present invention in example 5.

Fig. 6 is a cycle capacity diagram of a lithium-iron phosphate lithium full cell assembled using the electrolyte additive proposed by the present invention in example 9.

Fig. 7 is a graph of the cycle capacity of a lithium-sulfur full cell assembled in example 13 using the electrolyte additive proposed by the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Example 1

Dissolving 1mM fullerene polynitroxide (C60(NO2) n) in 1M lithium hexafluorophosphate solution of ethylene carbonate and diethyl carbonate (volume ratio of 1:1), stirring completely until dissolved, assembling a lithium symmetric battery using the electrolyte, lithium sheets and a diaphragm, and charging the battery at 0.5 mA/cm^-2The cycle test was performed at the current density of (1), as shown in fig. 1, in the experimental group using the ester electrolyte added with the additiveThe cells were said to be able to cycle stably for over 400 hours and to maintain a low overpotential, while the control had a large overpotential and was unable to cycle stably (the electrolyte in the control was simply a 1M solution of lithium hexafluorophosphate in ethylene carbonate and diethyl carbonate in a 1:1 volume ratio, with other cell structures and parameter settings remaining unchanged). The symmetric battery after the cycle is disassembled, the lithium sheet is taken out, and as shown in fig. 2, the scanning electron microscope photo of the lithium sheet in the experimental group of the electrolyte added with the additive is shown, metal lithium is uniformly deposited on the surface of the lithium sheet, no obvious dendritic crystal exists, and fullerene deposited on the surface can be seen, so that the fullerene derivative additive can obviously inhibit the growth of the dendritic crystal and prolong the cycle life.

Example 2

Dissolving 1mM fullerene polynitroxide (C60(NO2) n) in dioxolane and glycol dimethyl ether solution (volume ratio is 1:1) of 1M bis (trifluoromethyl) sulfimide lithium, completely stirring until the solution is dissolved, assembling the lithium-lithium symmetric battery by using the electrolyte, a lithium sheet and a diaphragm together, and performing lithium ion symmetric battery at 1mA cm^-2As shown in fig. 3, in the experimental group using ether electrolyte with additive, the symmetric cell can stably circulate for more than 400 hours, while the control group has larger overpotential and can not stably circulate (the electrolyte in the control group is simply dioxolane and glycol dimethyl ether solution of 1M bis (trifluoromethyl) sulfimide lithium, the volume ratio is 1:1, and the other cell structures and parameter settings are kept unchanged). Thus, the additive also has a remarkable effect in an ether electrolyte.

Example 3

The selected additive is fullerene polychloride (C60Cln), the selected electrolyte is a dioxolane and glycol dimethyl ether solution of 1M lithium bis (trifluoromethyl) sulfimide (volume ratio is 1:1), and the rest conditions are the same as those in the embodiment 1.

Example 4

Dissolving 1mM fullerene polychloride (C60Cln) in a 1M solution of lithium bis (trifluoromethyl) sulfonimide in dioxolane and glyme (volume ratio 1:1) and adding massCompletely stirring 1 percent of lithium nitrate until the lithium nitrate is dissolved, assembling a lithium-lithium symmetrical battery by using the electrolyte, a lithium sheet and a diaphragm together, and controlling the concentration of lithium nitrate at 1mA cm^-2The cycling test was performed at the current density of (1) as shown in fig. 4, in the experimental group using the ether electrolyte added with the additive and lithium nitrate, the symmetric cell was able to stably cycle for more than 600 hours, while the control groups 1 to 3 had a large overpotential and were unable to stably cycle (control group 1 was an electrolyte without any additive, i.e., the volume ratio of dioxolane and glyme solution of 1M bis (trifluoromethyl) sulfonimide lithium alone was 1: 1; control group 2 was an electrolyte with only 1% by mass of lithium nitrate additive added; control group 3 was an electrolyte with only 1mM fullerene derivative additive added, and other cell structures and parameter settings were kept constant). Thus illustrating that the additive may act synergistically with other additives.

Example 5

1mM fullerene polynitroxide (C60(NO2) n) is dissolved in 1M ethylene carbonate and diethyl carbonate solution of lithium hexafluorophosphate (volume ratio is 1:1), after the solution is completely stirred to be dissolved, the electrolyte, a lithium sheet, a copper sheet and a diaphragm are used for assembling a lithium copper half cell, a cycle test is carried out at a current density of 0.5mA cm < -2 >, the coulombic efficiency is obtained through the deposition stripping amount of lithium per cycle, as shown in figure 5, a coulombic efficiency test chart using an electrolyte additive shows that the stable charge and discharge cycle is more than 60 times, and a control group only has less than 30 cycles (the electrolyte in the control group is only ethylene carbonate and diethyl carbonate solution of 1M lithium hexafluorophosphate, the volume ratio is 1:1, and other cell structures and parameter settings are kept unchanged). Therefore, the electrolyte additive can obviously improve the stripping efficiency of lithium deposition, and further improve the performance of metal.

Example 6

The additive was used at a concentration of 10mM, the remainder being the same as in example 5.

Example 7

The additive type chosen was fullerene polybromide (C60Brn), the remainder being the same as in example 5.

Example 8

The additive types selected were fullerene polynitroxide (C60(NO2) n) and fluorocarbonate co-addition, the rest being the same as in example 5.

Example 9

Dissolving 1mM fullerene polynitroxide (C60(NO2) n) in a 1M solution of ethylene carbonate and diethyl carbonate of lithium hexafluorophosphate (volume ratio is 1:1), completely stirring until the solution is dissolved, assembling a lithium-lithium iron phosphate full cell by using the electrolyte, a lithium sheet, a lithium iron phosphate sheet and a diaphragm, and performing a cycle test under the multiplying power of 1C, wherein as shown in FIG. 6, the lithium-lithium iron phosphate full cell using the electrolyte additive can stably cycle for more than 200 cycles, and the capacity of a control group starts to obviously attenuate after less than 50 cycles (the electrolyte in the control group is a solution of ethylene carbonate and diethyl carbonate of 1M lithium hexafluorophosphate only, the volume ratio is 1:1, and the structures and parameter settings of other cells are kept unchanged). Thus, the electrolyte additive can obviously improve the cycle performance of the metal battery.

Example 10

The additive concentration chosen was 20mM, the rest being the same as in example 9.

Example 11

The additive type selected was fullerene polycarboxylate (C60(COOH) n), the rest being the same as in example 9.

Example 12

The additive species selected were fullerene polynitroxide (C60(NO2) n) and lithium polysulfide co-added, the remainder being the same as in example 5.

Example 13

Dissolving 1mM fullerene polynitroxide (C60(NO2) n) in a 1M solution of ethylene carbonate and diethyl carbonate of lithium hexafluorophosphate (volume ratio is 1:1), completely stirring until the solution is dissolved, assembling a lithium-sulfur full cell by using the electrolyte, a lithium sheet, a sulfur sheet and a diaphragm, and performing cycle test at a rate of 2C while performing different rate tests. As shown in fig. 7, the lithium-sulfur full cell using the electrolyte additive can stably cycle for more than 200 cycles and exert more than 2C rate900mAh g^-1The capacity of (2), whereas the control group only gave less than 800mAh g under the same test conditions^-1The capacity of the metal battery is reduced sharply in the circulation process (the electrolyte in the control group is only ethylene carbonate and diethyl carbonate solution of 1M lithium hexafluorophosphate, the volume ratio is 1:1, and other battery structures and parameter settings are kept unchanged), so that the electrolyte additive can obviously improve the circulation performance of the metal battery.

As shown in example 1 and fig. 1, the fullerene additive can significantly improve the cycle performance of the lithium-lithium symmetric battery in the ester electrolyte, thereby prolonging the service life of the lithium negative electrode.

As shown in example 2 and fig. 3, the fullerene additive can also significantly improve the cycle performance of the lithium-lithium symmetric battery in the ether electrolyte, thereby prolonging the service life of the lithium negative electrode.

As shown in example 4 and fig. 4, the fullerene additive can act together with other additives (such as lithium nitrate) to significantly improve the cycle performance of the lithium-lithium symmetric battery, thereby prolonging the service life of the lithium negative electrode.

As shown in example 5, fig. 5, the fullerene additive significantly improved the coulombic efficiency of the lithium negative electrode.

As shown in example 9 and fig. 6, the fullerene additive can significantly improve the service life and cycle performance of the lithium-lithium iron phosphate full cell.

As shown in example 13, fig. 7, the fullerene additive can significantly improve the service life and cycle performance of a lithium-sulfur full cell.

In addition to The above examples, The fullerene derivatives (C60Xn, n is a positive integer) used in The present invention may be one or more of fullerene polychloride (C60Cln), fullerene polyfluoride (C60Fn), fullerene polybromide (C60Brn), fullerene polyiodide (C60In), fullerene polynitroide (C60(NO2) n), fullerene polycarboxylate (C60(COOH) n), fullerene multiesteride (C60 (COOEt) n), fullerene polyhydroxyide (C60(OH) n), fullerene polyamino (C60 (NH2) n), fullerene polypiperazine (C60(C4H10N) n), fullerene polysulfonamide (C60 (SO2NH2) n), which are synthesized according to The prior art (for example, see Carbon 62, 413), thermal chemical (20120, 483) 421, 4812, Journal of Organic chemical (Journal of 483, 4812, 4826, 2005), organic Letters,2000, 2(23): 3663-. It is obvious that all of the functional group elements contained in these fullerene derivatives are elements that promote uniform deposition on the metal surface, and in the present invention, the fullerene derivative is most preferably a fullerene polynitroxide (C60(NO2) n).

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. The application of the fullerene derivative as an electrolyte additive is characterized in that the fullerene derivative is specifically added into the electrolyte of a metal battery as the electrolyte additive, can react with a metal cathode to generate a passivation film in situ, and prevents the direct contact between the metal cathode and the electrolyte, thereby reducing the consumption of the metal cathode;

the fullerene derivative is specifically one or more of fullerene polychloride, fullerene polyfluoride, fullerene polybromide, fullerene polyiodide, fullerene polynitroide, fullerene polycarboxylic acid compound, fullerene polyester base compound, fullerene polyhydroxy compound, fullerene polyamino compound, fullerene polypiperazine compound and fullerene polysulfonamide compound;

and the concentration of the fullerene derivative in the electrolyte is 0.1mM-100 mM;

the metal battery adopts a positive electrode material which is one or more of lithium iron phosphate, lithium cobaltate, lithium titanate, lithium manganate, ternary nickel-cobalt-manganese, ternary nickel-cobalt-aluminum, sulfur, oxygen, carbon dioxide and air; the adopted cathode material is one of metal lithium, metal sodium, metal potassium, metal zinc, metal magnesium and metal aluminum.

2. The use according to claim 1, wherein the fullerene derivative is added to the electrolyte of a metal battery as a single component additive or as a multicomponent electrolyte additive in combination with other components; wherein the other components are one or more of fluorinated carbonate, lithium nitrate, lithium polysulfide, lithium fluoride and vinylene carbonate.

3. The use according to claim 1, wherein the fullerene derivative additive is present in the electrolyte in a concentration of 1 mM.

4. A metal battery comprises a positive electrode material, a negative electrode material, a diaphragm and electrolyte, and is characterized in that the electrolyte mainly comprises an electrolyte additive and matrix electrolyte, wherein the electrolyte additive comprises a fullerene derivative; the fullerene derivative reacts with the metal cathode to generate a passivation film in situ, so that the direct contact between the metal cathode and an electrolyte can be prevented, and the consumption of the metal cathode is reduced;

the positive electrode material is one or more of lithium iron phosphate, lithium cobaltate, lithium titanate, lithium manganate, nickel cobalt manganese ternary, nickel cobalt aluminum ternary, sulfur, oxygen, carbon dioxide and air; the negative electrode material is one of metal lithium, metal sodium, metal potassium, metal zinc, metal magnesium and metal aluminum.

5. The metal battery as claimed in claim 4, wherein the fullerene derivative is added to the electrolyte of the metal battery as a single component additive or as a multi-component electrolyte additive in combination with other components; wherein the other components are one or more of fluorinated carbonate, lithium nitrate, lithium polysulfide, lithium fluoride and vinylene carbonate.

6. The metal cell of claim 4, wherein the electrolyte has an operating current of 0.01mA cm^-2～100mA cm^-2。

7. The metal battery of claim 6, wherein the electrolyte has an operating current of 0.5mA cm^-2。

8. The metal battery of claim 4, wherein the matrix electrolyte is selected from one or more of ether electrolyte, ester electrolyte, ether ester mixed electrolyte and ionic liquid electrolyte.

9. The metal battery of claim 4, wherein the separator is selected from the group consisting of PP separator, PE separator, PP/PE/PP separator, Al₂O₃Coating diaphragm, glass fiber diaphragm, PVDF diaphragm, PET/Al₂O₃One or more of a diaphragm, a cellulose diaphragm and an aramid diaphragm.